An internal combustion engine takes out the chemical reaction energy (thermal energy) of a fuel as kinetic energy. In such an internal combustion engine, gasoline, light oil, and so forth are used as a fuel. When gasoline is used as the fuel, the cycle of the internal combustion engine is “Otto-Cycle”. A number of technologies for expanding a positive work portion (a shaded area in FIG. 8) on a PV diagram, from a compression stroke to a combustion stroke during the Otto-cycle, have been developed (for example, JP-H8-296447A).
However, the related art technologies for expanding the positive work portion have following matters (1) to (3) to be overcome:
(1) Since an internal combustion engine body, a cooling water, and a lubricating oil are low in temperature at the time of cold start, a frictional force (at, for example, a sliding contact part between a piston and a cylinder) of an internal combustion engine is large. A fuel combustion may become unstable, so that fuel economy may be deteriorated and emission gas may increase;
(2) In a case where an internal combustion engine is mounted in an automobile, heating speed of passenger's compartment at the cold start is relatively low; and
(3) In an idle reduction control vehicle and a hybrid vehicle using a motor and an engine, the advantageous effects thereof cannot be fully exhibited before warm-up of the engine.